[G.M.]

You don't need a sight glass on the fuel pump. All you need is a laser pointed thermometer. When the top of the fuel pump gets to 135 degrees your in trouble. My pump will no longer get near 135 with the fuel return line will post the results later this week I expect the pump to remain below 125 degrees with the return line. A pressure gauge in the carb line will also show you when a vapor lock is coming. Fuel pressure drops as the pump gets hotter and when a full vapor lock is starting the gauge drops to a little less than 1 lb and starts jumping from less than lb to about a 1 lb and a half. G.M.